THE OVUM IN THE AMPHIBIA. 215 



ration either before or at the time of impregnation. With regard to the ovum of the 

 Tritons, I have recently made the following observations, since becoming acquainted 

 with the views of the authors named. 



A female Lissotriton punctatus, obtained on the 17th of May, produced several ova 

 on the morning of the 19th. Cleavage of the yelk (which, I may remark, was entirely 

 overlooked by RUSCONI* in his account of the Newts) commenced in two of these ova 

 at the expiration of eight hours, the temperature during the period having ranged from 

 56 FAHR. to 62 FAHR. On examining these ova very carefully about an hour before 

 the cleavage commenced, there were what I regarded as portions of the bodies of 

 spermatozoa on the surface, but certainly no traces of any in the interior. While 

 engaged in this examination the same female produced another egg, which she 

 inclosed as usual in a folded leaf. On this specimen, examined at the end of half an 

 hour, I could not detect any spermatozoa on the surface, which led me to imagine 

 that it had not been impregnated, a supposition which ultimately proved to be correct, 

 as no segmentation of the yelk took place in it. Some time after this, the tempera- 

 ture of the atmosphere being 62 FAHR., I saw the same newt enclosing another egg in 

 a leaf. This I immediately removed for examination, and thinking that this, like the 

 previously deposited egg, had not been impregnated, no traces of spermatozoa being 

 found on its surface, I placed it for about a minute in a small capsule filled with 

 water, into which a quantity of fluid had just been expressed from a male that had 

 been kept separate from the female. The fluid on examination was found to be com- 

 posed almost entirely of very active spermatozoa. The egg was examined three 

 minutes after immersion, and scarcely five minutes after it had been laid, and multi- 

 tudes of spermatozoa were then seen adhering to its surface. Most of them were still 

 vibrating rapidly, while others were motionless. But although I was able to distin- 

 guish every part of these bodies, I could not detect any in the act of penetrating, or 

 which had already penetrated into the substance of the envelope, and most certainly 

 not one was imbedded in the interior. Neither were there any in contact with the 

 yelk-membrane, or in the yelk-chamber of the envelope. 



The egg of the Newt is peculiarly fitted for an examination of this kind, from the 

 fact of the existence of this yelk-chamber, or space in the interior of the envelope. 

 This is formed by the gelatinous covering which the egg gains in the oviduct imbi- 

 bing fluid by endosmose and becoming expanded immediately it comes into contact 

 with water, when the inner layer separates from the vitellary membrane, with which it 

 has been in contact within the duct ; and as the outer layers more and more expand, 

 the yelk, covered only by the vitellary membrane, is left free in a large cavity in the 

 interior, surrounded by a thin fluid. The spermatozoa of the Newts, as is well known, 

 are of large size, and are easily recognized ; so that in the event of their having pene- 

 trated the egg-covering before it leaves the duct, or at the moment of its expansion, 

 or after the chamber has been formed in it, they can hardly escape observation. 



* Amours des Salamandres Aquatiques, 4to. Milan, 1821. 



